Abstract: Located in alluvial plain, the middle and lower Changjiang River suffers from frequent flood disasters. Embankment is the first barrier to protect life and property along the river. The Jingjiang River reach in the middle Changjiang River is exposed to a more serious flood control situation because of large amount of high flood peak and complex river-lake relation. In this research, the flood risk in the flood protection region enclosed by Songzi Levee of upper Jingjiang River reach is assessed. The flood routing process in mainstream Changjiang River and the studied flood protection region in the presence of levee break during a 1 000-year event flood is simulated using a 1-D and 2-D coupled mathematical model with generalized river network of Jingjiang River and Dongting Lake water system. Maximum flood depth, inundation duration, maximum flow velocity,affected population, and flood losses are selected as risk elements to analyze the distribution of flood risk. The article is divided into two parts. Present here is the second part to expound the flood routing process and risk distribution characteristics in the protected zone. In practical flood control, attention should be paid to the Yuanshi levee which would give rise to the most severe loss once breach occurs.

Key words: flood risk, flood protection region, flood propagation, Jingjiang River reach, Songzi levee